1. Field of the Invention
The present invention relates to a pressing apparatus, and more particularly, to a pressing apparatus having a plurality of rollers forming a chamber.
2. Description of the Related Art
For many years attempts have been made to use external air pressure to force water out of a paper web. Rather than compress a sheet at a press nip to the point where hydraulic pressure drives water out, as is the case in normal wet pressing, it was reasoned that more water could be removed, and sheet bulk could be maintained, if air pressure could be applied to supplement roller nip generated hydraulic pressures. One such attempt involves providing a multi-roller structure forming a closed chamber, wherein air is circulated through the chamber to convect moisture out of the paper web. Providing efficient sealing of such a chamber, and in particular providing chamber end sealing for the rollers, has proven to be problematic due to the relatively large rotary contact surfaces which must be effectively sealed.
Accordingly, a need exists for an improved pressing apparatus which provides efficient sealing of a chamber, and in particular, provides efficient end sealing between the roller ends and the chamber end panels.